Well, I am looking at getting some 17 by 8 wheels.

I have been told that to do 17 by 8's, I need a -11mm offset. Is this correct?

What is the difference between offset and backspacing, or is there any difference?

I am looking at some TTII's or something, not quite sure though.

 

Backspace is the distance from the back edge of the wheel to the hub mounting surface.

Offset is the distance from its hub mounting surface to the centerline of the wheel.

Backspace determines how well the wheel fits inside the wheel well. Offset is just a reference number. When ordering rims, they'll only want to know how much backspace you want.

If you have an 8" rim with 4" backspace then offset is zero.

 

Ok, so what backspacing do I need then?

 

Anyone?

 

here is a good link for you to read

https://www.thirdgen.org/forums/susp...t=10+inch+rims

 

In that link a bunch of guys are running a 4.5BS on the front with a 17 by 8, is that the same BS that I need for the rear to run a 17 by 8?

 

An 8" wide wheel with "0" offset should have approximately 4.5" of backspacing.

Here's how it works:
An 8" wide rim actually measures 9" from outside edge to outside edge. (Advertised rim widths are determined from measuring the distance between the inner beads)

So, an 8" wide rim with "0" offset will have 4.5" of backspacing. Next, there are 25.4mm to an inch, so offset of 6mm is equal to about .2" (let's call it 1/4"), 12mm is equal to about .5" ...and so on.

 

Many aftermarket rims such as Weld only sell rims with 1/2" backspacing. 3-1/2", 4-1/2", 5-1/2" etc.

 

so wouldnt it be safe to say that a 9" wide wheel in the front would need an offset of 13mm to keep the wheel in the same location as the stock wheel?

http://www.1010tires.com/WheelOffsetCalculator.asp